Process for production of polymer polyols

ABSTRACT

The present invention provides a process for preparing a polymer polyol (PMPO) by alkoxylating a starter compound(s) having active hydrogen atoms in the presence of a double metal cyanide (DMC) catalyst, radical initiator(s) and optionally PMPO stabilizers and simultaneously polymerizing unsaturated monomer(s) with radical initiator(s). The polymer polyols (PMPOs) made by the inventive process may find use in the preparation of polyurethane foams and elastomers.

FIELD OF THE INVENTION

The present invention relates in general, to polymer polyols, and morespecifically, to a process for preparing a polymer polyol (PMPO) byalkoxylating a starter compound having active hydrogen atoms in thepresence of a double metal cyanide (DMC) catalyst and simultaneouslypolymerizing unsaturated monomer(s) with radical initiator(s).

BACKGROUND OF THE INVENTION

Polymer polyols (PMPOs) are employed in the preparation of polyurethanefoams and elastomers and are extensively used on a commercial scale.Polyurethane foams made from such polymer polyols have a wide variety ofuses. The two major types of polyurethane foams are slabstock and moldedfoam. Polyurethane slabstock foams are used in carpet, furniture andbedding applications. Molded polyurethane foams are used in theautomotive industry for a broad range of applications.

Polymer polyols are typically produced by polymerizing one or moreethylenically unsaturated monomers dissolved or dispersed in a preparedpolyol in the presence of a free radical catalyst to form a stabledispersion of polymer particles in the polyol. Typically, polymerpolyols used to produce polyurethane foams having higher load-bearingproperties than those produced from unmodified polyols were preparedusing acrylonitrile monomer; however, many of those polymer polyols haveundesirably high viscosity.

Polyurethane foams having high load-bearing properties are predominantlyproduced using polymer polyols that are prepared from a high styrenecontent monomer mixture (for example, 65 to 75 percent styrene).However, polymer polyols produced from such high styrene monomermixtures often fail to satisfy the ever more demanding needs ofindustry, including acceptable viscosity, strict stability requirementsand increased load-bearing properties.

Stability and low viscosity of polymer polyols are of increasingimportance to polyurethane foam manufacturers due to the development ofsophisticated, high speed and large volume equipment and systems forhandling, mixing and reacting polyurethane-forming ingredients. Polymerpolyols must meet certain minimum polymer particle size requirements toavoid plugging or fouling filters, pumps and other parts of such foamprocessing equipment in relatively short periods of time.

Numerous attempts have been made to produce polymer polyols that willsatisfy the above criteria. In particular, Japanese laid-open patentapplication, Kokai No. 6-228247, teaches a semibatch process for makinga polymer polyol by the sequential addition of oxide monomer and itspolymerization followed by addition of vinyl monomers and theirpolymerization in the same reactor. Although the Japanese laid-openapplication teaches that removal of the DMC catalyst is not required, itfails to even suggest that the processing steps could be anything otherthan sequential. Thus, while one skilled in the art might infer fromreading Kokai '247 that DMC catalysts do not interfere with free radicalpolymerization, Kokai '247 provides no guidance concerning whether freeradical polymerization interferes with DMC catalysis.

A number of workers have patented continuous processes for producingpolyols, such as U.S. Pat. No. 5,689,012, issued to Pazos et al., whichdiscloses a continuous process for the preparation of polyoxyalkylenepolyethers using DMC catalysts as the polyoxyalkylation catalyst andemploying continuous addition of alkylene oxide in conjunction withcontinuous addition of starter and catalyst to a continuousoxyalkylation reactor. The polyether products are said to beexceptionally well suited for use in polymer forming systems,particularly polyurethanes. In the process of Pazos et al., polyolsynthesis begins with introduction of catalyst/starter into thecontinuous reactor, initiation of oxyalkylation, and while oxyalkylationprogresses, continuous addition of catalyst, starter and alkylene oxidewith continuous removal of polyol product. The process of Pazos et al.adds “fresh” catalyst or pre-activated catalyst.

U.S. Pat. No. 5,777,177, issued to Pazos, teaches a process for makingdouble metal cyanide-catalyzed polyols involving making a polyetherpolyol by polymerizing an epoxide in the presence of a double metalcyanide (DMC) catalyst, a continuously added starter (S_(c)), andoptionally, an initially charged starter (S_(i)). The continuously addedstarter has at least about 2 equivalent percent of the total starterused (total starter=S_(c)+S_(i)). Although conventional processes formaking DMC-catalyzed polyols charge the entire starter to be used to thereactor at the start of the polymerization, the process of Pazos addsboth the epoxide and the S_(c) continuously to the reaction mixtureduring the polymerization.

U.S. Pat. No. 5,059,641, issued to Hayes et al., discloses very lowviscosity PMPOs having high styrene/acrylonitrile ratios and goodstability which are produced with epoxy-modified polyols as dispersants.The epoxy-modified polyol dispersant may be made by one of threemethods: (1) adding the epoxy resin internally to the modified polyol,(2) capping or coupling a polyol not containing an epoxy resin with sucha resin, or (3) providing the epoxy resin both internally to the polyoland as a cap or coupler. Epoxy-modified polyols having a hydroxyl toepoxy ratio of about 8 or less, made by one of these techniques, aresaid to be superior dispersants and provide polymer polyols havinghigher styrene contents, improved stability and viscosity properties.

Numerous patents disclose the continuous and semi-batch preparation ofPMPOs, including processes where the base polyol is a DMC-catalyzedpolyol. Heretofore, as exemplified in those patents, the process issequential, i.e., a polyol is prepared first which is reacted withunsaturated monomers in a subsequent step.

Therefore, a need exists in the art for a simultaneous process forpreparing a polymer polyol (PMPO) directly from starter compound havingactive hydrogen atoms, alkylene oxide(s), double metal cyanide (DMC)catalyst, unsaturated monomer(s) and radical initiator(s).

SUMMARY OF THE INVENTION

Accordingly, the present invention provides a process for preparing apolymer polyol (PMPO) directly from a starter compound(s) having activehydrogen atoms, in the presence of a double metal cyanide (DMC)catalyst, unsaturated monomer(s) radical initiator(s) and optionallyPMPO stabilizers, by alkoxylating the starter compound(s) andsimultaneously polymerizing the unsaturated monomer(s) with radicalinitiator(s). Because the inventive process may be carried out in onevessel, it may eliminate the need for multi-step or multistage processesand thus make more efficient use of reactors and storage tanks. Theprocess of the present invention may be continuous or semibatch and thepolymer polyols made thereby may find use in the preparation ofpolyurethane foams and elastomers.

These and other advantages and benefits of the present invention will beapparent from the Detailed Description of the Invention herein below.

DETAILED DESCRIPTION OF THE INVENTION

The present invention will now be described for purposes of illustrationand not limitation. Except in the operating examples, or where otherwiseindicated, all numbers expressing quantities, percentages, hydroxylnumbers, functionalities and so forth in the specification are to beunderstood as being modified in all instances by the term “about.”

The present invention provides a process for preparing a polymer polyol(PMPO) involving combining in a reactor at least one starter compoundcontaining active hydrogen atoms, a double metal cyanide (DMC) catalyst,at least one unsaturated monomer, at least one radical initiator, atleast one alkylene oxide and optionally, at least one polymer polyol(PMPO) stabilizer, simultaneously alkoxylating the starter andpolymerizing the monomer with at least one radical initiator andremoving the polymer polyol (PMPO) from the reactor.

The present invention also provides a continuous process for preparing apolymer polyol (PMPO) involving a) introducing, into a continuousreactor, sufficient DMC catalyst/initial starter mixture to initiatepolyoxyalkylation of the initial starter after introduction of alkyleneoxide into the reactor, b) continuously introducing into the reactor atleast one continuously added starter, c) continuously introducing intothe reactor fresh DMC catalyst and/or further DMC catalyst/furtherstarter mixture such that catalytic activity is maintained, d)continuously introducing into the reactor at least one unsaturatedmonomer, e) continuously introducing into the reactor at least oneradical initiator, f) continuously introducing into the reactor at leastone alkylene oxide to produce a polymer polyol product; and g)continuously removing the polymer polyol product from the reactor.

The starter compound in the inventive process may be any compound havingactive hydrogen atoms. Preferred starter compounds include, but are notlimited to, compounds having number average molecular weights from 18 to2,000, more preferably, from 62 to 2,000, and having from 1 to 8hydroxyl groups. Examples of such starter compounds include, but are notlimited to, polyoxypropylene polyols, polyoxyethylene polyols,polytetatramethylene ether glycols, glycerol, propoxylated glycerols,propylene glycol, ethylene glycol, tripropylene glycol, trimethylolpropane alkoxylated allylic alcohols, bisphenol A, pentaerythritol,sorbitol, sucrose, degraded starch, water and mixtures thereof.

In those embodiments of the inventive process wherein the process iscontinuous, the starter used to prepare the DMC catalyst/starter mixtureis preferably an oligomeric starter, more preferably an oxyalkylatedoligomer based on the same low molecular weight starter whose continuousaddition is to be used in the continuous process. For example, wherepropylene glycol is to be continuously added to the reactor, a suitableoligomeric starter useful in preparing the activated catalyst/startermixture would be a 300 Da to 1,000 Da molecular weight polyoxypropyleneglycol. The same oligomeric starter would be suitable for use wheredipropylene glycol or water will be the continuously added starters.Where glycerine is to be the continuously added starter, anoxypropylated glycerine polyol having a molecular weight of 400 Da to1,500 Da is advantageously used. However, a feature of the presentprocess is the ability to utilize essentially monomeric starters such asethylene glycol, propylene glycol, and the like. Thus, the starter usedto prepare the catalyst/starter mixture may be the same as thecontinuously added starter.

The continuously added starter may be water, ethylene glycol, diethyleneglycol, triethylene glycol, propylene glycol, dipropylene glycol,tripropylene glycol, 1,2-, 1,3-, and 1,4-butylene glycols, neopentylglycol, glycerine, trimethylolpropane, triethylolpropane,pentaerythritol, α-methylglucoside, hydroxymethyl-, hydroxyethyl-, andhydroxypropylglucosides, sorbitol, mannitol, sucrose,tetrakis[2-hydroxyethyl and 2-hydroxypropyl]ethylene diamines and othercommonly used starters. Also suitable are monofunctional starters suchas methanol, ethanol, 1-propanol, 2-propanol, n-butanol, 2-butanol,2-ethylhexanol, and the like, as well as phenol, catechol,4,4′-dihydroxybiphenyl, 4,4′-dihydroxydiphenylmethane, etc. Othersuitable starters include those described in U.S. Pat. Nos. 3,900,518;3,941,849; and 4,472,860, the entire contents of which are hereinincorporated by reference thereto.

The continuously added starter may be essentially any polyoxyalkylenepolymer or copolymer or suitable initiator for the production thereof,which has a molecular weight less than the desired product weight. Thus,the molecular weight of the continuously added starter may vary from 18Da (water) to 45,000 Da (high molecular weight polyoxyalkylene polyol).It is much preferred to use continuously added starters with molecularweight less than 1,000 Da, preferably less than 500 Da, and mostpreferably less than 300 Da.

The term “continuous” as used herein may be defined as a mode ofaddition of a relevant catalyst or reactant in such manner so as tomaintain an effective concentration of the catalyst or reactantsubstantially continuously. Catalyst input, for example, may be trulycontinuous, or may be in relatively closely spaced increments. Likewise,continuous starter addition may be truly continuous, or may beincremental. It would not detract from the present process toincrementally add a catalyst or reactant in such a manner that the addedmaterial's concentration decreases to essentially zero for some timeprior to the next incremental addition. However, it is preferable thatcatalyst concentration be maintained at substantially the same levelduring the majority of the course of the continuous reaction, and thatlow molecular weight starter be present during the majority of theprocess. Incremental addition of catalyst and/or reactant which does notsubstantially affect the nature of the product is still “continuous” asthat term is used herein.

The alkylene oxides useful in the present process include, but are notlimited to, ethylene oxide, propylene oxide, oxetane, 1,2- and2,3-butylene oxide, isobutylene oxide, epichlorohydrin, cyclohexeneoxide, styrene oxide, and the higher alkylene oxides such as the C₅-C₃₀α-alkylene oxides. It is generally undesirable to employ ethylene oxidealone, but mixtures of propylene oxide and ethylene oxide with highethylene oxide content, i.e., up to 85 mol percent, may be usedeffectively. Propylene oxide or mixtures of propylene oxide withethylene oxide or another alkylene oxide are preferred. Otherpolymerizable monomers may be used as well, e.g., anhydrides and othermonomers as disclosed in U.S. Pat. Nos. 3,404,109, 5,145,883 and3,538,043, the entire contents of which are herein incorporated byreference thereto.

The process of the present invention may employ any double metal cyanide(DMC) catalyst. Suitable double metal cyanide (DMC) catalysts are wellknown to those skilled in the art. Double metal cyanide complex (DMC)catalysts are non-stoichiometric complexes of a low molecular weightorganic complexing agent and optionally other complexing agents with adouble metal cyanide salt, e.g., zinc hexacyanocobaltate.

Exemplary double metal cyanide (DMC) complex catalysts include thosesuitable for preparation of low unsaturation polyoxyalkylene polyetherpolyols, such as disclosed in U.S. Pat. Nos. 3,427,256; 3,427,334;3,427,335; 3,829,505; 4,472,560; 4,477,589; and 5,158,922. The doublemetal cyanide (DMC) catalysts more preferred in the process of thepresent invention are those capable of preparing “ultra-low”unsaturation polyether polyols. Such catalysts are disclosed in U.S.Pat. Nos. 5,470,813, 5,482,908, and 5,545,601, the entire contents ofwhich are herein incorporated by reference thereto. Most preferred inthe process of the present invention are those zinc hexacyanocobaltatecatalysts prepared by the methods described in U.S. Pat. No. 5,482,908.

The catalyst concentration is chosen so as to ensure a good control ofthe polyoxyalkylation reaction under the given reaction conditions. Thecatalyst concentration is preferably in the range from 0.0005 wt. % to 1wt. %, more preferably in the range from 0.001 wt. % to 0.1 wt. %, mostpreferably in the range from 0.001 to 0.01 wt. %, based on the amount ofpolyether polyol to be produced. The catalyst may be present in theprocess of the present invention in an amount ranging between anycombination of these values, inclusive of the recited values.

As those skilled in the art are aware, an organic complexing ligand maybe included with the DMC catalyst. Any organic complexing ligand may bepart of the DMC catalyst in the process of the present invention, suchas the organic complexing ligands described in U.S. Pat. Nos. 3,404,109,3,829,505, 3,941,849, 5,158,922 and 5,470,813, as well as in EP 700 949,EP 761 708, EP 743 093, WO 97/40086 and JP 4145123. Such organiccomplexing ligands include water-soluble organic compounds withheteroatoms, such as oxygen, nitrogen, phosphorus or sulfur, which canform complexes with the DMC compound. Preferred as organic complexingligands, are alcohols, aldehydes, ketones, ethers, esters, amides,ureas, nitriles, sulfides and mixtures thereof. More preferred organiccomplexing ligands include water-soluble aliphatic alcohols, such as,for example, ethanol, isopropanol, n-butanol, iso-butanol, sec-butanoland tert-butanol. Tert-butanol is most preferred.

The DMC catalysts in the process of the present invention may optionallycontain at least one functionalized polymer. “Functionalized polymer” asused herein is a polymer or its salt that contains one or morefunctional groups including oxygen, nitrogen, sulfur, phosphorus orhalogen. Examples of functionalized polymers preferred in the inventiveprocess include, but are not limited to, polyethers, polyesters,polycarbonates, polyalkylene glycol sorbitan esters, polyalkylene glycolglycidyl ethers, polyacrylamides, poly(acrylamide-co-acrylic acids),polyacrylic acids, poly(acrylic acid-co-maleic acids),poly(N-vinylpyrrolidone-co-acrylic acids), poly(acrylicacid-co-styrenes) and the salts thereof, maleic acids, styrenes andmaleic anhydride copolymers and the salts thereof, block copolymerscomposed of branched chain ethoxylated alcohols, alkoxylated alcoholssuch as NEODOL (sold commercially by Shell Chemical Company), polyether,polyacrylonitriles, polyalkyl acrylates, polyalkyl methacrylates,polyvinyl methyl ethers, polyvinyl ethyl ethers, polyvinyl acetates,polyvinyl alcohols, poly-N-vinylpyrrolidones, polyvinyl methyl ketones,poly(4-vinylphenols), oxazoline polymers, polyalkyleneimines,hydroxyethylcelluloses, polyacetals, glycidyl ethers, glycosides,carboxylic acid esters of polyhydric alcohols, bile acids and theirsalts, esters or amides, cyclodextrins, phosphorus compounds,unsaturated carboxylic acid esters and ionic surface- orinterface-active compounds. Polyether polyols are most preferably usedin the process of the present invention.

Where used, functionalized polymers may be present in the DMC catalystin an amount of from 2 to 80 wt. %, preferably, from 5 to 70 wt. %, morepreferably, from 10 to 60 wt. %, based on the total weight of DMCcatalyst. The functionalized polymers may be present in the DMC catalystin an amount ranging between any combination of these values, inclusiveof the recited values.

The DMC catalyst may or may not be activated prior to use in theinventive process. Activation, when desired, involves mixing thecatalyst with a starter molecule having a desired number ofoxyalkylatable hydrogen atoms, and adding alkylene oxide, preferablypropylene oxide or other higher alkylene oxide under pressure andmonitoring the reactor pressure. The reactor may be advantageouslymaintained at a temperature of from 90° C. to 150° C., more preferablyfrom 100° C. to 140° C. and most preferably from 110° C. to 130° C. Anoticeable pressure drop in the reactor indicates that the catalyst hasbeen activated. The same alkylene oxide as is to be employed in PMPOproduction may be used to prepare activated catalyst, or a differentalkylene oxide may be employed. With higher alkylene oxides having lowvapor pressure, a volatile alkylene oxide such as ethylene oxide,oxetane, 1,2-butylene oxide, 2,3-butylene oxide, or isobutylene oxidemay be employed in lieu of or in conjunction with the higher alkyleneoxide to facilitate pressure monitoring. Alternatively, other methods ofmeasuring alkylene oxide concentration (GC, GC/MS, HPLC, etc.) may beused. A noticeable reduction in free alkylene oxide concentrationindicates activation.

A particularly advantageous feature of the present invention is theability to employ “fresh” DMC catalysts without activation. DMC catalystactivation, as described hereinabove, not only involves additionaloperator attention, thus increasing processing cost, but requires apressurized reaction vessel, increasing capital costs as well. “Fresh”catalyst as used herein is freshly prepared, non-activated DMC catalyst,i.e., non-activated DMC catalyst in solid form or in the form of aslurry in low molecular weight starter, polyoxyalkylated low molecularweight starter, or a non-starter liquid. Most preferably, all or asubstantial portion of the liquid phase of a fresh DMC catalyst mixturewill include the same low molecular weight starter used for continuousstarter addition, a polyoxyalkylated low molecular weight starter. Theability of the inventive process to employ fresh, non-activated DMCcatalyst allows for significant economies in the commercial productionof polymer polyols.

Suitable unsaturated monomers for use in the inventive process include,but are not limited to, butadiene, isoprene, 1,4-pentadiene,1,6-hexadiene, 1,7-octadiene, styrene, acrylonitrile, methacrylonitrile,α-methylstyrene, methylstyrene, 2,4-dimethylstyrene, ethyl styrene,isopropylstyrene, butylstyrene, substituted styrenes, such ascyanostyrene, phenylstyrene, cyclohexylstyrene, benzylstyrene,nitrostyrene, N,N-dimethylaminostyrene, acetoxystyrene, includinghalogenated styrenes, methyl 4-vinylbenzoate, phenoxystyrene, p-vinyldiphenyl sulfide, p-vinylphenyl phenyl oxide, acrylic and substitutedacrylic monomers such as acrylic acid, methacrylic acid, methylacrylate, 2-hydroxyethyl acrylate, 2-hydroxyethyl methacrylate, methylmethacrylate, cyclohexyl methacrylate, benzyl methacrylate, isopropylmethacrylate, octyl methacrylate, ethyl α-ethyoxyacrylate, methylα-acetoaminoacrylate, butyl acrylate, 2-ethylhexyl acrylate, phenylacrylate, phenyl methacrylate, N,N-dimethylacrylamide,N,N-dibenzylacrylamide, N-butylacrylamide, methacrylyl formamide, vinylesters, vinyl ethers, vinyl ketones, vinyl acetate, vinyl alcohol, vinylbutyrate, isopropenylacetate, vinyl formate, vinyl acrylate, vinylmethacrylate, vinyl methoxy acetate, vinyl benzoate, vinyl toluene,vinyl naphthalene, vinyl methyl ether, vinyl ethyl ether, vinyl propylethers, vinyl butyl ethers, vinyl 2-ethylhexyl ether, vinyl phenylether, vinyl 2-methoxyethyl ether, methoxybutadiene, vinyl 2-butoxyethylether, 3,4-dihydro-1,2-pyran, 2-butoxy-2′-vinyloxy diethylether, vinyl2-ethylmercaptoethyl ether, vinyl methyl ketone, vinyl ethyl ketone,vinyl phenyl ketone, vinyl ethyl sulfide, vinyl ethyl sulfone,N-methyl-N-vinyl acetamide, N-vinylpyrrolidone, vinyl imidazole, divinylsulfide, divinyl sulfoxide, divinyl sulfone, sodium vinyl imidazole,divinyl sulfide, divinyl sulfoxide, divinyl sulfone, sodium vinylsulfonate, methyl vinyl sulfonate, N-vinyl pyrrole, dimethyl fumarate,dimethyl maleate, maleic acid, crotonic acid, fumaric acid, itaconicacid, monomethyl itaconate, t-butylaminoethyl methacrylate,dimethylaminoethyl methacrylate, glycidyl acrylate, ally alcohol, glycolmonoesters of itaconic acid, vinyl pyridine, maleic anhydride,maleimide, N-substituted maleimides, such as N-phenylmaleimide and thelike. Preferred unsaturated monomers in the present invention are bothstyrene and acrylonitrile.

The amount of vinyl monomer(s) fed to the reactor is selected to achievethe desired vinyl polymer solids content in the final polymer polyolproduct. The solids level may range from as little as 5 wt. % to upwardsof 45 wt. %, preferably from 10 wt. % to 30 wt. %, most preferably from15 wt. % to 25 wt. %, based on the total weight of the components. If alower solids content polymer polyol is desired, the solids content maybe lowered by dilution of the higher solids polyol with further amountsof the same base polyol or other non-polymer polyol, or by blending witha polymer polyol of lesser solids content.

Preferred as radical initiators in the inventive process are the freeradical type of vinyl polymerization initiators, such as the peroxidesand azo compounds. Specific examples include2,2′-azo-bis-isobutyronitrile (AIBN), dibenzoyl peroxide, lauroylperoxide, di-t-butyl peroxide, diisopropyl peroxide carbonate, t-butylperoxy-2-ethylhexanoate, t-butylperneodecanoate, t-butylperbenzoate,t-butyl percrotonate, t-butyl perisobutyrate, di-t-butyl perphthalateand 2,2′-azo-bis(2-methylbutanenitrile) available from DuPont as VAZO67.

The free radical initiator concentration in the formulation is notcritical and can be varied within wide limits. As a representativerange, the concentration can vary from 0.01 to 5.0 wt. % or greater,based on the total weight of the components. The free radical initiatorand temperature should be selected so that the initiator has areasonable rate of decomposition with respect to the hold-up time in thereactor for a continuous flow reactor or the feed time for a semi-batchreactor.

The process of the present invention may optionally include one or morepolymer polyol (PMPO) stabilizers. Suitable stabilizers are those knownin the art which stabilize polymer polyols prepared by traditionalmethods. The stabilizer may be free of induced unsaturation such asthose disclosed in U.S. Pat. No. 5,059,641, the entire contents of whichare incorporated herein by reference thereto. The stabilizer may containreactive induced unsaturations which are in general prepared by thereaction of the selected reactive unsaturated compound with a polyol.The terminology “reactive induced unsaturated compound,” refers to anycompound capable of forming an adduct with a polyol, either directly orindirectly, and having carbon-to-carbon double bonds which areadequately reactive with the particular monomer system being utilized.More specifically, compounds containing α,β-unsaturation are preferred.Suitable compounds satisfying this criteria include the maleates,fumarates, acrylates, and methacrylates. Although not α,β-unsaturatedcompounds, polyol adducts formed from substituted vinyl benzenes such aschloromethylstyrene likewise may be utilized. Illustrative examples ofsuitable α,β-unsaturated compounds which may be employed to form theprecursor stabilizer include maleic anhydride, fumaric acid, dialkylfumarates, dialkyl maleates, glycol maleates, glycol fumarates,isocyanatoethyl methacrylate,1,1-dimethyl-m-isopropenylbenzyl-isocyanate, methyl methacrylate,hydroxyethyl methacrylate, acrylic and methacrylic acid and theiranhydrides, methacroyl chloride and glycidyl methacrylate. The level ofethylenic unsaturation in the precursor stabilizer may vary widely. Theminimum and maximum levels of unsaturation are both constricted by thedispersion stability that the precursor stabilizer is capable ofimparting to the polymer polyol composition. The specific level ofunsaturation utilized will further depend on the molecular weight of thepolyol used to prepare the precursor stabilizer. More particularly,unsaturation levels of at least 0.04 meq/gm, up to 0.10 meq/gm areparticularly suitable. The stabilizer may also be a preformed stabilizeror contain solids which act as “seeds”. References for preformedstabilizers and “seeds” include: U.S. Pat. Nos. 5,488,086; 6,013,731;5,990,185; 6,455,603; 5,814,699; 5,196,476; and U.S. PublishedApplication Nos. 2003-0220410, and 2003-0181598.

The simultaneous polymer polyol production process of the presentinvention may be continuous or semi-batch. In the semi-batch process,the reactor vessel should preferably be equipped with an efficient meansof agitation, for example, an impeller-type stirrer or recirculationloop. A continuous process may be implemented in one or more reactors inseries, with the second reactor facilitating substantially completereaction of monomers with continuous product takeoffs, or may beperformed in a continuous tubular reactor with incremental additions ofmonomers along the length of the reactor. The first reactor preferablyshould be a continuous, stirred, back-mixed reactor. The components arepumped into the first reactor continuously through an in-line mixer toassure complete mixing of the components before they enter the reactor.The contents of the reactor are well mixed with a residence time of atleast 8 minutes, preferably greater than 30 minutes. Residence times aretypically between one and eight hours. The product of the first reactoris collected as it flows continuously out of the reactor through abackpressure regulator, which preferably has been adjusted to give somepositive backpressure in the reactor.

The inventive process may also be carried out in the presence of anorganic solvent, reaction moderator, and/or chain transfer agent.Examples of these materials include, but are not limited to, benzene,toluene, ethylbenzene, xylene, hexane, mercaptans such asdodecylmercaptan, halogenated hydrocarbons, particularly thosecontaining bromine and/or iodine, and the like and enol-ethers.

Following polymerization, volatile constituents, in particular thosefrom the solvent and residues of monomers are preferably stripped fromthe product by vacuum distillation, optionally, in a thin layer orfalling film evaporator. The monomer-free product may be used as is, ormay be filtered to remove any large particles that may have beencreated.

The polymer polyols made by the inventive process are suitable for thepreparation of polyurethane foams and elastomers.

EXAMPLES

The present invention is further illustrated, but is not to be limited,by the following examples. The following materials were used in theExamples:

DMC Catalyst zinc hexacyanocobaltate catalyst made essentially accordingto U.S. Pat. No. 5,482,908; Polyol A 56 OH No., all-PO starter triol,made according to present Example 1; Polyol B dispersant no. 6 accordingto U.S. Pat. No. 5,059,641; Polyol C 112 OH No. starter triol containing6 wt % ethylene oxide and 180 ppm of activated DMC catalyst; VAZO 672,2′-azo-bis(2-methylbutanenitrile) available from DuPont; and LHT-240240 OH No, all-PO triol, available from Bayer Polymers LLC.

Example 1 Preparation of Polyol A (Activated Starter)

A one-liter reactor (Parr Instrument Co.) was charged with a 1500 MWtriol activated starter (300 g) containing DMC Catalyst (150 ppm). Twofeeds were prepared: a three-gallon pressure vessel (Pope ScientificInc.) was charged with propylene oxide (PO) (8800 g) and a one-gallonpressure vessel (Pope Scientific Inc.) was charged with a mixture of 41%LHT-240 and 59% of a 1500 MW triol activated starter (2989 g) containingDMC catalyst (150 ppm).

The reactor was heated to 130° C. while pulling vacuum and isolated.Propylene oxide (30 g) was added and the feed stopped. After threeminutes, the pressure dropped from 20 psia to 1 psia. The PO feed wascontinued at 6 g/min. until a total of 300 g of PO had been added. Thefeed was stopped. At this point, the pressure in the reactor measured 3psia. A back pressure regulator between the reactor and the collectionvessel was set at 54 psia and the valve connected to the back pressureregulator opened. Both feeds were started (6.6 g/min for PO and 3.4g/min for the activated starter mix). The feeds were continued until theproduct overflowed the reactor and filled the collection vessel. When itwas estimated that there was 400 g in the collection vessel, the vesselwas heated to 130° C. When 700 g was in the vessel, the flow wasdiverted to a slop tank for five minutes while the polyol was strippedand drained. In this way, seven “cuts” were collected of five residencetimes (5000 g). At this point, the reactor was isolated and cooled whilefull of an all PO triol having a hydroxyl number of about 56. The finalcut had an OH No. of 55.2 meq/g KOH and 0.004 unsaturation.

Example 2 Preparation of PMPO by Continuous Process

Two feeds were prepared as detailed below.

Feed A Feed B VAZO 67  26.4 g propylene oxide 8800.0 g styrene 489.0 gacrylonitrile 238.0 g 1.5 K activated starter* 1322.0 g  LHT-240 925.0 g*1.5 K activated starter contained 150 ppm DMC catalyst

The reactor from Example 1 (with Polyol A produced in Example 1) wasopened to the back pressure regulator, which was set to 54 psia. Thereactor was heated to 115° C. and both feeds A and B were started. Thetargeted feed rates were 4.5 g/min. for Feed A and 6.6 g/min. for Feed B(PO). The same procedure as in Example 1 was followed. To collect afraction, flow was diverted to a slop tank and the material in thecollection vessel stripped. A total of 896 g of Feed B (PO) and 568 g ofFeed A were fed to the reactor before the run was stopped. The contentsof the reactor were analyzed for viscosity (1218 cst at 25° C.) andparticle size (average mean diameter was 2.52 microns). The polymerpolyol had an OH No. of 50 meq/g KOH.

Example 3 Preparation of PMPO by Continuous Process

The procedure disclosed in Example 1 was followed to provide a fullreactor of Polyol A. This reaction was conducted at 115° C. The reactionwas stopped and two new feeds were prepared as detailed below.

Feed A Feed B 1.5 K act. starter* 1744 g (58.1%) acrylonitrile  257 g(4.7%) LHT-240 1221 g (40.7%) styrene  530 g (9.6%) VAZO 67  35 g (1.1%)propylene oxide 4731 g (85.7%) Total 3000 g Total 5518 g *1.5 K act.starter contained 150 ppm DMC catalyst

The two feeds were turned on, targeting 3.5 g/min. for Feed A and 7.7g/min. for Feed B. These feed rates target 10% solids. Nine fractions of650 g were collected for a total of six residence times. Fractions 8 and9 were analyzed. Viscosity was 1156 cst at 25° C. The average particlesize was 6.7 microns diameter. The polymer polyol produced had an OH No.of 50 meq/g KOH.

Example 4 Preparation of PMPO by Semi-Batch Process (Prophetic)

Feed Mix: Propylene Oxide 791 g Ethylene Oxide 140 g Styrene 280 gAcrylonitrile 120 g VAZO 67  10 g

A two-liter pressure vessel is charged Polyol A (233 g), Polyol B (36g), and DMC catalyst (0.035 g). With stirring, the reactor contents areheated under vacuum while sparging with nitrogen to 120° C. and held at120° C. for 15 minutes. After stopping vacuum and nitrogen sparge, about30 g of the feed mix is added to the reactor over a period of about 10minutes. The feed is stopped to ensure the pressure in the reactordrops. After confirming activation, the remainder of the feed mix isadded to the reactor over a period of about 3 hours at 120° C. withstirring. Upon completion of the addition, the dispersion is held atreaction temperature for 0.25-0.5 hours. The reaction mixture isstripped of residual monomers for 1.5-2.5 hours at 110-130° C., and lessthan 5 mm Hg yielding a polymer polyol product having a hydroxyl numberof approximately 36 meq/g KOH.

Example 5 Preparation of PMPO by Semi-Batch Process (Prophetic)

Feed Mix: Propylene Oxide 840 g Ethylene Oxide 111 g Glycerin 16.1 g Propylene glycol  3.1 g  Styrene 280 g Acrylonitrile 120 g VAZO 67  10 g

A two-liter pressure vessel is charged Polyol C (194 g) and Polyol B (36g). With stirring, the reactor contents are heated under vacuum whilesparging with nitrogen to 120° C. and held at 120° C. for 15 minutes.After stopping vacuum and nitrogen sparge about 30 g of the feed mix isadded to the reactor over a period of about 10 minutes. The feed isstopped to ensure the pressure in the reactor drops. After confirmingactivation, the remainder of the feed mix is added to the reactor over aperiod of about 3 hours at 120° C. with stirring. Upon completion of theaddition, the dispersion is held at reaction temperature for 0.25-0.5hours. The reaction mixture is stripped of residual monomers for 1.5-2.5hours at 110-130° C. and less than 5 mm Hg yielding a polymer polyolproduct having a hydroxyl number of approximately 36 meq/gm KOH.

The foregoing examples of the present invention are offered for thepurpose of illustration and not limitation. It will be apparent to thoseskilled in the art that the embodiments described herein may be modifiedor revised in various ways without departing from the spirit and scopeof the invention. The scope of the invention is to be measured by theappended claims.

What is claimed is:
 1. A continuous process for the preparation of apolymer polyol (PMPO) comprising: a) introducing into a continuousreactor sufficient DMC catalyst/initial starter mixture to initiatepolyoxyalkylation of the initial starter after introduction of alkyleneoxide into the reactor; b) continuously introducing into the reactor atleast one continuously added starter; c) continuously introducing intothe reactor fresh DMC catalyst and/or further DMC catalyst/furtherstarter mixture such that catalytic activity is maintained; d)continuously introducing into the reactor at least one unsaturatedmonomer; e) continuously introducing into the reactor at least oneradical initiator; f) continuously introducing into the reactor at leastone alkylene oxide and optionally, at least one polymer polyol (PMPO)stabilizer, to produce the polymer polyol (PMPO); and g) continuouslyremoving the polymer polyol (PMPO) from the reactor, wherein the processsimultaneously alkoxylates the starter and polymerizes the unsaturatedmonomer, thereby simultaneously forming a polyoxyalkylene polyol andforming discrete polymer particles to produce a polymer polyol (PMPO) inone reactor.
 2. The continuous process according to claim 1, wherein theinitial starter is chosen from polyoxypropylene polyols, polyoxyethylenepolyols, polytetatramethylene ether glycols, glycerol, propoxylatedglycerols, propylene glycol, ethylene glycol, diethylene glycol,triethylene glycol, dipropylene glycol, tripropylene glycol, trimethylolpropane, alkoxylated allylic alcohols, bisphenol A, pentaerythritol,sorbitol, sucrose, degraded starch, water and mixtures thereof.
 3. Thecontinuous process according to claim 1, wherein the at least onecontinuously added starter is chosen from polyoxypropylene polyols,polyoxyethylene polyols, polytetatramethylene ether glycols, glycerol,propoxylated glycerols, propylene glycol, ethylene glycol, diethyleneglycol, triethylene glycol, dipropylene glycol, tripropylene glycol,trimethylol propane, alkoxylated allylic alcohols, bisphenol A,pentaerythritol, sorbitol, sucrose, degraded starch, water and mixturesthereof.
 4. The continuous process according to claim 1, wherein the atleast one unsaturated monomer is chosen from butadiene, isoprene,1,4-pentadiene, 1,6-hexadiene, 1,7-octadiene, styrene, acrylonitrile,methacrylonitrile, α-methyl-styrene, methylstyrene, 2,4-dimethylstyrene,ethyl styrene, isopropylstyrene, butylstyrene, cyanostyrene,phenylstyrene, cyclohexylstyrene, benzylstyrene, nitrostyrene,N,N-dimethylaminostyrene, acetoxystyrene, halogenated styrenes, methyl4-vinylbenzoate, phenoxystyrene, p-vinyl diphenyl sulfide, p-vinylphenylphenyl oxide, acrylic acid, methacrylic acid, methyl acrylate,2-hydroxyethyl acrylate, 2-hydroxyethyl methacrylate, methylmethacrylate, cyclohexyl methacrylate, benzyl methacrylate, isopropylmethacrylate, octyl methacrylate, ethyl α-ethyoxyacrylate, methylα-acetoaminoacrylate, butyl acrylate, 2-ethylhexyl acrylate, phenylacrylate, phenyl methacrylate, N,N-dimethylacrylamide,N,N-dibenzylacrylamide, N-butyl-acrylamide, methacrylyl formamide, vinylesters, vinyl ethers, vinyl ketones, vinyl acetate, vinyl alcohol, vinylbutyrate, isopropenylacetate, vinyl formate, vinyl acrylate, vinylmethacrylate, vinyl methoxy acetate, vinyl benzoate, vinyl toluene,vinyl naphthalene, vinyl methyl ether, vinyl ethyl ether, vinyl propylethers, vinyl butyl ethers, vinyl 2-ethylhexyl ether, vinyl phenylether, vinyl 2-methoxyethyl ether, methoxybutadiene, vinyl 2-butoxyethylether, 3,4-dihydro-1,2-pyran, 2-butoxy-2′-vinyloxy diethylether, vinyl2-ethylmercaptoethyl ether, vinyl methyl ketone, vinyl ethyl ketone,vinyl phenyl ketone, vinyl ethyl sulfide, vinyl ethyl sulfone,N-methyl-N-vinyl acetamide, N-vinylpyrrolidone, vinyl imidazole, divinylsulfide, divinyl sulfoxide, divinyl sulfone, sodium vinyl imidazole,divinyl sulfide, divinyl sulfoxide, divinyl sulfone, sodium vinylsulfonate, methyl vinyl sulfonate, N-vinyl pyrrole, dimethyl fumarate,dimethyl maleate, maleic acid, crotonic acid, fumaric acid, itaconicacid, monomethyl itaconate, t-butylaminoethyl methacrylate,dimethylaminoethyl methacrylate, glycidyl acrylate, ally alcohol, glycolmonoesters of itaconic acid, vinyl pyridine, maleic anhydride, maleimideand N-substituted maleimides.
 5. The continuous process according toclaim 1, wherein the at least one unsaturated monomer is a mixture ofstyrene and acrylonitrile.
 6. The continuous process according to claim1, wherein the at least one radical initiator is chosen from2,2′-azo-bis-isobutyronitrile (AIBN), dibenzoyl peroxide, lauroylperoxide, di-t-butyl peroxide, diisopropyl peroxide carbonate, t-butylperoxy-2-ethylhexanoate, t-butylperneo-decanoate, t-butylperbenzoate,t-butyl percrotonate, t-butyl perisobutyrate, di-t-butyl perphthalateand 2,2′-azo-bis(2-methylbutanenitrile).
 7. The continuous processaccording to claim 1, wherein the at least one radical initiator is2,2′-azo-bis(2-methylbutanenitrile).
 8. The continuous process accordingto claim 1, wherein the at least one alkylene oxide is chosen fromethylene oxide, propylene oxide, 1,2- and 2,3-butylene oxide,isobutylene oxide, epichlorohydrin, cyclohexene oxide and styrene oxide.9. The continuous process according to claim 1, wherein the at least onealkylene oxide is propylene oxide.
 10. The continuous process accordingto claim 1, wherein the at least one polymer polyol (PMPO) stabilizer isan epoxy-modified polyol.
 11. The continuous process according to claim1 further including a solvent or a polymer control agent.
 12. Thecontinuous process according to claim 1, wherein the polymer polyol(PMPO) stabilizer is a polyether having induced unsaturation.